dark glasses vs spectacles

dark glasses and spectacles both are nouns.

Word	Noun	Adjective	Verb	Adverb
dark glasses	Yes	No	No	No
spectacles	Yes	No	No	No

As nouns, spectacles is a hypernym of dark glasses; that is, spectacles is a word with a broader meaning than dark glasses:

dark glasses: (plural) spectacles that are darkened or polarized to protect the eyes from the glare of the sun
spectacles: (plural) optical instrument consisting of a frame that holds a pair of lenses for correcting defective vision

Other hypernyms of dark glasses include eyeglasses, glasses, specs.

dark glasses (noun)	spectacles (noun)
(plural) spectacles that are darkened or polarized to protect the eyes from the glare of the sun	(plural) optical instrument consisting of a frame that holds a pair of lenses for correcting defective vision